A number of movable platforms or cages are currently known for lifting an operator, other personnel or equipment, from ground level to an elevated position on large sized machinery, such as machinery used in the mining or earth moving industry where the operator or other personnel may alight adjacent to the cab of the vehicle, or where equipment may be unloaded. Such platforms or cages also serve for lowering the operator, personel or equipment from that elevated position. Examples of such platforms or cages are shown in U.S. Pat. Nos. 3,986,724 and 4,217,971. Support devices are provided to hold the platform or cage in its elevated position adjacent to the vehicle. The currently known support devices however, have proved difficult to use and do not support the platform or cage in a stable secure position adjacent to the vehicle cab. Additionally, moving the platform or cage to a position where it may be engaged by the known support devices has also proved difficult.